STRUCTURE OF CH3(CH2)17SH SELF-ASSEMBLED ON THE AG(111) SURFACE - AN INCOMMENSURATE MONOLAYER

We describe the first experimental study of the molecular structure of the self-assembled monolayer of CH3(CH2)17SH formed on the Ag(111) surface. Using both low-energy He diffraction and grazing incidence X-ray diffraction, we show that the monolayer formed on Ag is both incommensurate and rotated with respect to the Ag lattice, with a lattice spacing which is very similar to n-alkane chains in bulk hydrocarbon crystals. Lastly, by comparing the results of the X-ray and He diffraction experiments on the same sample, we observe that the outermost surface of the monolayer is less ordered than the interior.